This invention relates to the disproportionation of olefins. In another aspect this invention relates to a disproportionation catalyst. In still another aspect, this invention relates to a novel method for producing a disproportionation reaction.
The disproportionation, or metathesis, of olefins is a reaction in which one or more olefinic compounds are transformed into other olefins of different molecular weights. The disproportionation of an olefin to produce one olefin of a higher molecular weight and one olefin of a lower molecular weight can also be referred to as self-disproportionation. For example, propene can be disproportionated to ethylene and cis- and trans-2-butene. Another type of disproportionation involves the codisproportionation of two different olefins to form still other olefins. An example would be the reaction of one molecule of 2-butene with one molecule of 3-hexene to produce two molecules of 2-pentene.
The term "disproportionation reaction" as used herein is intended to include all variations of disproportionation reactions including:
(1) The disproportionation of an acyclic mono- or polyene having at least three carbon atoms into other mono- or polyenes of both higher and lower number of carbon atoms; for example, the disproportionation of propylene yields ethylene and butenes; the disproportionation of 1,5-hexadiene yields ethylene and 1,5,9-decatriene;
(2) The conversion of an acyclic mono- or polyene having three or more carbon atoms and a different acyclic mono- or polyene having three or more carbon atoms to produce different acyclic olefins; for example, the conversion of propylene and isobutylene yields ethylene and isopentene;
(3) The conversion of ethylene and an internal acyclic mono- or polyene having four or more carbon atoms to produce other olefins having a lower number of carbon atoms than that of the acyclic mono- or polyenes; for example, the conversion of ethylene plus 4-methylpentene-2 yields 3-methylbutene-1 and propylene;
(4) The conversion of ethylene or an acyclic mono- or polyene having three or more carbon atoms with a cyclic mono- or cyclic polyene to produce an acyclic polyene having a higher number of carbon atoms than that of any of the starting materials; for example, the conversion of cyclohexene and 2-butene yields 2,8-decadiene; the conversion of 1,5-cyclooctadiene and ethylene yields 1,5,9-decatriene;
(5) The conversion of one or more cyclic mono- or cyclic polyenes to produce a cyclic polyene having a higher number of carbon atoms than any of the starting materials; for example, the conversion of cyclooctene yields cyclohexadiene;
(6) The conversion of an acyclic polyene having at least 7 carbon atoms and having at least 5 carbon atoms between any two double bonds to produce acyclic and cyclic mono- and polyenes having a lower number of carbon atoms than that of the feed; for example, the conversion of 1,7-octadiene yields cyclohexene and ethylene; or
(7) The conversion of one or more acyclic polyenes having at least three carbon atoms between any two double bonds to produce acyclic and cyclic mono- and polyenes generally having both a higher and lower number of carbon atoms than that of the feed material; for example, the conversion of 1,4-pentadiene yields 1,4-cyclohexadiene and ethylene.
Among the catalysts that have been developed for disproportionation are those comprising inorganic refractory oxides containing a catalytic amount of molybdenum oxide. The present invention is based upon the discovery of a way to improve the activity of such a catalyst.